INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy)...
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Transcript of INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy)...
![Page 1: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/1.jpg)
INTAGRAFInternational Alpine Gravity Field Course(27.08.2005 – 09.09.2005, Merano, Italy)
Topography and DEMTopography and DEM
Modelling mountains
![Page 2: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/2.jpg)
Topography and DEMTopography and DEM
TIN: Vector model (Triangulated Irregular Network)
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
•History:Official elevation network had to be used for a 3D model,
•Can integrate different sources of data,
•Very flexible, can model even vertical or overhanging topography
![Page 3: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/3.jpg)
Topography and DEMTopography and DEM
TIN: Vector model (Triangulated Irregular Network)
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 4: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/4.jpg)
Topography and DEMTopography and DEM
Raster model (DEM – Digital Elevation Model)
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
•Data are sorted in a regular, quadratic grid
•Ideal for scan-lines of satellites
•Easy to treat / to implement
BUT
•Contains redundant information in flat areas
can be very large!
![Page 5: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/5.jpg)
Topography and DEMTopography and DEM
Raster model (DEM – Digital Elevation Model)
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 6: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/6.jpg)
Topography worldwideTopography worldwide
GEBCO Ocean Mapping at Intergovernmental Oceanographic Commission (IOC)
http://www.ngdc.noaa.gov/mgg/gebco/gebco.html
Topography / bathymetry worldwide complete: 1 Minute academic license : 99 pound sterling
GTOPO30 U.S. Geological Survey's EROS Data Center a compilation of different raster and vector sources, completed in 1996Only onshore data, 30 seconds
http://edcdaac.usgs.gov/gtopo30/gtopo30.aspftp://edcftp.cr.usgs.gov/pub/data/gtopo30/global/
DVD 78 $FTP download free of charge
SRTM Shuttle Radar Topography Mission (NASA, U.S.G.S. EROS Data Center ) Only onshore data between 60° N and 56°S, 3 seconds, in the United States 1 second
Satellite mission: Feb. 11th - 22nd 2000
http://srtm.usgs.gov/
FTP download free of chargeINTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 7: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/7.jpg)
Different spatial resolutionDifferent spatial resolution
11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 1246
46.1
46.2
46.3
46.4
46.5
46.6
46.7
46.8
46.9
47
3712 values
G EBCO 1 M inute (ca. 1.8 km )
11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 1246
46.1
46.2
46.3
46.4
46.5
46.6
46.7
46.8
46.9
14641 va lues
G TO PO 30 30 Seconds (ca. 0.9 km )
11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 1246
46.1
46.2
46.3
46.4
46.5
46.6
46.7
46.8
46.9
47
1442401 values
SRTM 3 Seconds (ca. 90 m )
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 8: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/8.jpg)
SRTMSRTM
Most frequently used data set
Resolution: 3“ (approx. 90 meters)Height levels: 1 mCoordinates (datum) WGS84Error horizontal (relative): 15 m Error vertical (relative): 6 m available via ftp://e0mss21u.ecs.nasa.gov/srtm/or – using an input scheme - http://seamless.usgs.gov/
Data format: .htg or .bil – binary format in files of 1 x 1 degree
Contains data gaps- offshore- in water covered areas- in areas of rough topography
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 9: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/9.jpg)
SRTM – The method ISRTM – The method I
Figures from: http://srtm.usgs.gov/
60 m
The fixed baseline interferometry uses the traveltime difference between two radar beams, which are sent to the Earth, reflected at the surface, and then received by two antennas at a distance of 60 m.
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 10: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/10.jpg)
SRTM – The method IISRTM – The method IIRadar Holograms
Radar ImageRadar Image
Interferogram
+ PhaseInformation
+ PhaseInformation
Digital Elevation Model
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 11: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/11.jpg)
SRTM – data gapsSRTM – data gaps
11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 1246
46.1
46.2
46.3
46.4
46.5
46.6
46.7
46.8
46.9
47
Data Gaps
(here marked red)exist in areas of rough topography or water covered areas.
cause problems with- visualization- calculation of the topographic correction- volume and/or surface calculations
May be filled bya) interpolation, orb) other data (gtopo30)
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 12: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/12.jpg)
SRTM - Vertical ErrorSRTM - Vertical Error
10 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 1154
54.1
54.2
54.3
54.4
54.5
54.6
54.7
54.8
54.9
55
10 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 1154
54.1
54.2
54.3
54.4
54.5
54.6
54.7
54.8
54.9
55
-40
-30-20-10
010
203040
5060
708090100110120130140150160
Shaded reliefFlat map
(vertical 6 m relative)causes severe problems in areas with flat topography
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 13: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/13.jpg)
Terrain Correction - AmountsTerrain Correction - Amounts
Topographic Correction [mGal]0 10 20 30 40
0
20
40
60
Southern Andes No:13512 Northern Andes No:12034
Transalp No:468 Meran No:443
Topographic Correction Values in Selected Areas
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
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Topographic correction onshoreTopographic correction onshore
-5,25 - -5.00 -4,5 - -4,25 -3,75 - -3,5 -3,0 - -2,75 -2,25 - -2,0 -1,5 - -1,25 -0,75 - 0,5 0 - 0,25
0
10
20
30
40
50
60
Land
Histogram of topographic reduction values in percent. Values of histogram classes given in 10-5 m/s2.
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
![Page 15: INTAGRAF International Alpine Gravity Field Course (27.08.2005 – 09.09.2005, Merano, Italy) Topography and DEM Modelling mountains.](https://reader036.fdocuments.in/reader036/viewer/2022081602/55142baf5503466d1a8b4d65/html5/thumbnails/15.jpg)
Topographic correction offshoreTopographic correction offshore
-70 - -65 -55 - -50 -40 - -35 -25 - -20 -10 - -5 5 - 10 20 - 25 35 - 40 50 - 55 65 - 70
0
5
10
15
20
25
Offshore
Histogram of topographic reduction values in percent. Values of histogram classes given in 10-5 m/s2.
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
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15012510075500 25
0
-5
Calculation radius [km]
Topographic correction for 440 stations in Meran area (Alps, Italy):Difference to correction for the radius 167 km.
INTAGRAF 2005 – Sabine Schmidt, “Topography and DEM”
Terrain Correction - RadiusTerrain Correction - Radius